Page:Report of the Board of Inquiry into the Helderberg air disaster.djvu/96

Rh The horizontal stabiliser trim is normally electrically controlled and hydraulically operated, but it can be controlled manually in the event of an electrical system failure. The elevators and rudders are cable controlled and hydraulically operated. All of these control cables are routed along the centre of the fuselage crown area and so are the pitot pressure and static tubes to the rudder ratio control modules, the pitot tubes to the elevator Q feel unit and stabiliser rate control sensing unit. If the control cables and/or the fuselage structure were not severely damaged by heat there should not have been any loss of pitch or yaw control.

As the electrical wiring, pitot pressure and pitot static pipe lines to the pitch and yaw control units had probably been damaged by the fire, the manufacturer of the aeroplane was requested to advise what the effects of such damage could have been on the flight characteristics of the aeroplane. The following answers were given to the following questions: